<b>Marine Scrubber Systems</b>
Since January 1st, 2020 the sulphur cap is in force. Before that date fuel oil used by vessels mainly took the form of HSFO (High Sulphur Fuel Oil) containing a sulphur content of 3.50%. The IMO 2020 initiative sets a regulatory, upper limit on the sulphur content of fuel oil to be used by ships at 0.5%. The aim of the new regulation is to decrease the amount of sulphur emissions global shipping produces and it affects around 60,000 ships currently in operation. Vessels, therefore, need to comply with the IMO 2020 regulation and one option is to install a scrubber that acts as a gas cleaning system to reduce the sulphur content from HSFO.
Scrubbers need to be retroactively fitted to the vessel and by the end of 2019 only 2% of the global shipping fleet has already implemented one. However, more than 11.8% of the world’s containership capacity will be fitted with scrubbers by January 2020 according to analyst Alphaliner. Scrubber fitted boxships will account for approximately 5.9% of the total number of containerships by that date. These figures reveal that containerships fitted with a scrubber will be rather of bigger size.
Depending on the price gap between LSFO/MGO and HSFO continuing with burning HSFO while complying with the sulphur cap could be a significant competitive advantage in the stiff cost competition in shipping nowadays. Depite their huge investment srubbers are said to have only a payback within a year if fuel oil spreads stay wide.
Scrubbers spray alkaline water into the exhaust gas stream to neutralise sulphur oxides (SOx). 2/3 to 3/4 of all scrubber installations are of open loop type. The remaining are closed-loop systems and hybrids.
An open-loop system neutralises the SOx by taking advantage of the natural alkalinity of seawater which is subsequently cleaned and discharged back into the ocean. A typical closed-loop system uses freshwater mixed with sodium hydroxide; the wash water is then purified and recirculated, and the resulting residual sludge is stored in tanks and disposed of at the next port that offers appropriate facilities.
In the meantime several countries have announced a ban on using open-loop scrubbers in their ports and inland waters, among them Belgium, Germany, India, Ireland, Lithuania, Latvia, Norway, UAE and parts of the United States in order to protect their waters from the wash water. Most recently, Singapore, China and Malaysia joined that list. This system is criticized from several sides for transferring pollution from the air to the ocean.
Although the washwater must meet strict criteria, so that discharge washwater should have a pH of no less than 6.5, the industry is facing a fierce debate over whether open-loop scrubbers represent an environmentally sound option.
The Exhaust Gas Cleaning System Association (EGCSA) as well as the Clean Shipping Alliance (CSA) 2020 which are promoting the open-loop system, arguing against unilateral actions by ports and regions and promise their ongoing effort to ensure that governmental bodies, port authorities and decision makers are adequately informed of current research findings and data which have not identified any short- or long-term impact on the environment. In addition, according to CSA, several port authorities including some in Japan and more than 20 various ports in Europe, the Americas, Asia and Australia indicated they had no intention of banning the use of open-loop scrubbers in their waters. Similarly, a report released by Japan’s Ministry of Land, Infrastructure, Transport and Tourism (MLIT) concludes that the operation of open-loop scrubbers with high sulphur fuel oil is not only safe, it is also preferable to burning low sulphur fuel alone.
Contrary to open-loop scrubbers closed-loop systems can be used irrespective of the composition of the water where the vessel is operating, including estuaries and freshwater bodies such as the Great Lakes. Open-loop scrubbers, on the other hand, do not work effectively in waters of low salinity.
So far shipowners prefer open-looped systems over closed because they are very easy to install, require less maintenance and don’t require storage for waste materials – as water is directly pumped back into the sea after onboard treatment.
There are also high sophisticated hybrid scrubbers, which switch between open and closed-loop depending on situations such as local rules which may or may not prohibit the discharge of water.
Finally, time will tell what is the ideal option based on the specific conditions or whether vessels will switch to using other means. The ultimate decision is up to the shipowner.
Marine Scrubber Systems
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